A purine nucleoside analogue, ribavirin (generic name), is known as an antiviral agent having a wide range of antiviral spectrum.
The blood clotting disorders generally represent blood diseases having hemostatic abnormality and/or coagulation abnormality and include coagulation disorders, platelet disorders, aplastic anemia, and leukemia. The hemostatic abnormality and/or coagulation abnormality of these disorders lead to the bleeding tendency.
For treatment of hemophilia (A or B) as a typical example of the coagulation disorder, replacement therapy is generally performed to supplement the defective or reduced clotting factor. The replacement therapy, however, imposes the heavy physical and economical burdens on the patients and has the relative inconvenience due to the requirement of intravenous injections. The repeated bleeding causes articular disorders. While the risk of virus contamination in transfusion products for replacement therapy has been significantly reduced, there is still a possibility of unknown viral infection like HIV virus infection or hepatitis C virus infection through the blood products in past days. There is also an unsolved problem of expression of an antibody (inhibitor) against the injected factor. Gene therapy to the hemophilia patients has not yet been established.
The hemophilia patients may be required to prevent or treat the HIV virus infection or hepatitis C virus infection due to the use of virus-infected injections. The patient with HIV infection or with virus-induced hepatic disorder may have the blood clotting disorder as the complication due to the decreased coagulation factor or thrombocytopenia.
It has been reported that the combined administration of ribavirin and an interferon decreased the dosage of warfarin as an antithrombotic agent (see Non-Patent Document 1).    Patent Document 1: Japanese Patent Laid-Open No. 2001-181201    Non-Patent Document 1: Shulman A., Ann. Pharmacother. 2002, 36, 72-74